I keep mine in the unheated garage too...it should be fine as stated above, if kept cool and dry. The shelf life of feed is some what of a joke, I worked at a feed company for a while...how you store it is much more important than how long you store it.

Mat Peirce
1.25 acre southeast Iowa pond
LMB, BG, YP, WE, HSB, RES, BCP